Ever since i swapped out my stock head for one with work done, pnp, valve job, milled .030", stg 2 cams, dual valve springs, ti retainers, adj cam gears, arp head studs, my idle has been messed up. I shouldn't actually say idle b/c it doesn't really idle.
When the car is at normal operating temperature the engine will rev up to 1200-1500rpm and bog down to 2,3,4,500rpm usually. It doesn't usually stall out, unless i have driven on the highway for 20-30 minutes. So after highway driving i have to adjust the idle screw just so it doesn't stall when i come to a stop before i can give it that ever-so-slight amount of gas so it doesn't stall.
I have a vafc and the sensor check says TPS is 4.45V @ closed throttle. I've reset and adjusted the TPS after i put on a 64mm bored b16 t/b with a new FITV (so the FITV is out of the question) But when i come to a stop and give it that "ever-so-slight" amount of gas the throttle reading on the vafc is 0.0 but clearly i am giving it gas b/c it steadies out the idle.
I pulled the IACV off and there was no build up on the screen. But can the IACV still be malfunctioning? I have replaced the PCV as well. Today i got out the old vacuum pressure guage. It jumped between 12-15 inches of vacuum at idle.
Any help is appreciated.

 

I think you may have the same problem as me. A malfunctioning primary O2. I too have a JDM B16A1 (PW0 to be exact). It was fine when I first installed the motor but I have found lately that I have that odd idle problem.

I attribute it to being under the car one day to find the the connector on the O2 sensor plug that connects my O2 extension cable laying on the header pipe. Slightly burned. So I think the cable, and in your case maybe the O2 sensor itself, being *slightly* damaged is causing this. It is not completely dead, just sending the wrong or incorrect signals to the ECU.

 

i have no CEL either. Would the o2 be pooched and not throw a code?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by zman &raquo;</TD></TR><TR><TD CLASS="quote">Ever since i swapped out my stock head for one with work done, pnp, valve job, milled .030", stg 2 cams, dual valve springs, ti retainers, adj cam gears, arp head studs, my idle has been messed up. I shouldn't actually say idle b/c it doesn't really idle.
When the car is at normal operating temperature the engine will rev up to 1200-1500rpm and bog down to 2,3,4,500rpm usually. It doesn't usually stall out, unless i have driven on the highway for 20-30 minutes. So after highway driving i have to adjust the idle screw just so it doesn't stall when i come to a stop before i can give it that ever-so-slight amount of gas so it doesn't stall.
I have a vafc and the sensor check says TPS is 4.45V @ closed throttle. I've reset and adjusted the TPS after i put on a 64mm bored b16 t/b with a new FITV (so the FITV is out of the question) But when i come to a stop and give it that "ever-so-slight" amount of gas the throttle reading on the vafc is 0.0 but clearly i am giving it gas b/c it steadies out the idle.
I pulled the IACV off and there was no build up on the screen. But can the IACV still be malfunctioning? I have replaced the PCV as well. Today i got out the old vacuum pressure guage. It jumped between 12-15 inches of vacuum at idle.
Any help is appreciated.</TD></TR></TABLE>


1st i assume you've checked all vacuum lines. Next check for gasket of tb and manifold for leak. Turn on the engine and let it runs til it gets warm (let it runs even with erratic idling up and down) Third, take out ur intake, there are two holes inside tb, then use a pieace of cloth or something that air prove and totally block those two holes. while you're blocking, listen to the idle sound. The idling sound should calm down or even possible or stalling the engine. If it does't calm down, then i';m sure u got a vacuum leak either at vacuum hose or gaskets. If it doesn't calm the fock down and you want to check for vacuum leak, go buy yourself a Starting-fluid at Kragen or Autozone, then spray it on the tb's gasket (around the tb's gasket, something the leak located beneath the tb) CONSTANSTLY and listen to the ilding sound, if it calms the fock down then u got a leak right there. Do the same at manifold gasket and some vacuum lines.

The SIAC-V (controlled by ecu) and FITV (controlled by coolant) are hardly get broke or malfunctioning. pm if you have any question

gl man